Control apparatus in an engine suction conduit to prevent increase in the fuel-air ratio due to adhered fuel on the conduit walls

ABSTRACT

A second throttle valve is placed in a suction conduit through which an air fuel mixture passes to the engine cylinders, the second throttle valve being disposed downstream of a manually operated first throttle valve and being connected to a device which is responsive to the suction pressure prevailing in the conduit when the first throttle valve is closed such that the second throttle valve is also closed, there being an air inlet conduit opening into the supply conduit to supply a measured burst of ambient air into the supply conduit downstream of the second throttle valve to compensate for admission to the cylinders of fuel adhering to the walls of the supply conduit whereby the air fuel ratio of the mixture supplied to the cylinders is maintained. Additionally, the first and second throttle valves are coupled together and a spring is interposed between the second throttle valve and the device responsive to the suction pressure in the supply conduit so that when the first throttle valve is opened during acceleration, the second throttle valve is opened therewith against the opposition of the spring irrespective of the pressure prevailing in the supply conduit.

United States Patent CONTROL APPARATUS IN AN ENGINE SUCTION CONDUIT TOPREVENT INCREASE IN THE FUEL- AIR RATIO DUE TO ADHERED FUEL ON THECONDUIT WALLS 8 Claims, 2 Drawing Figs.

111:. CI. 50 2 3 9 0 F02m 23/02; F02m 23/04 Field of Search .L123/119152", 119D, 124,971;

[56] References Cited UNITED STATES PATENTS 2,017,878 10/1935 Vanderpoel123/97 2,129,608 9/1938 Vanderpoel.... 123/119 2,129,609 9/1938Vanderpoel 123/1 19 Primary Examiner-Wendell E. Burns AttarneyWaters,Roditi, Schwartz & Nissen ABSTRACT: A second throttle valve is placed ina suction conduit through which an air-fuel mixture passes to the enginecylinders, the second throttle valve being disposed downstream of amanually operated first throttle valve and being connected to a devicewhich is responsive to the suction pressure prevailing in the conduitwhen the first throttle valve is closed such that the second throttlevalve is also closed, there being an air inlet conduit opening into thesupply conduit to supply a measured burst of ambient air into the supplyconduit downstream of the second throttle valve to compensate foradmission to the cylinders of fuel adhering to the walls of the supplyconduit whereby the air-fuel ratio of the mixture supplied to thecylindersis maintained. Additionally, the first and second throttlevalves are coupled together and a spring is interposed between thesecond throttle valve and the device responsive to the suction pressurein the supply conduit so that when the first throttle valve is openedduring acceleration, the second throttle valve is opened therewithagainst the opposition of the spring irrespective of the pressureprevailing in the supply conduit.

BRIEF SUMMARY OF THE INVENTION It is usual in an internal combustionengine that when the diaphragm l urged downwards by a spring 9, and theinterior of the upper chamber a is in communication with a negativepressure responsive opening 11 formed in the pipe 4 downstream of thesecond throttle valve 7. The diaphragm I0 is connected to the secondthrottle valve 7 through a connect- I ing rod 12. Thus, when a negativepressure is produced when engine is operated, liquid fuel adheres to theinner surface of the walls of the suction conduit thereof. Consequently,when the throttle valve is closed at the time of an engine brakeoperation, the adhering fuel is induced by the large negative pressurewhich is produced to flow into the engine cylinders so that the fuel-airration is greatly increased and-may produce unfavorable and irregularcombustion.

In order to overcome this, it is known to employ a second throttle valvein the fuel-air mixture supply conduit downstream of the conventional,manually operated first throttle valve. This second throttle valve isconnected to a device which at the time of an engine brake operationcauses the second throttle valve to be closed by the negative pressureprevailing in the conduit due to the closing of the first conduit.

This known apparatus, however, is deficient in that, though the adheredfuelwithin the conduit upstream of the second throttle valve isprevented from flowing into the engine cylinders, the adhered fuelwithin the conduit downstream of the second throttle valve cannot beintercepted and it flows into the engine cylinders as in theconventional arrangementto still cause an increase in the fuel-airratio.

The known apparatus is additionally deficient in that when the firstthrottle valve is then opened for acceleration, the second throttlevalve remains closedarid is not opened immediately due to the fact thatthe negative pressure operated apparatus is still in an operativecondition by the negative pressure which initially remains, wherebyrapid acceleration cannot be obtained.

An object of this invention is to provide a second throttle valvearrangement as above which is free from the deficiencies as mentionedhereinbefore and is characterized in that, an air supply conduit whichopens into the interior of the passage for the fuel-air mixturedownstream of the second throttle valve is opened only at the initialstage of the period when the second throttle valve has been closed tosupply ambient air to said passage and hence maintain the fuel-air ratioin said passage. Additionally, the first throttle valve and the secondthrottle valve are connected together and there is interposed betweenthe second throttle valve and the negative pressure operated device aspring for allowing a relative opening movement of the second throttlevalve so that when the first throttle valve is opened, the secondthrottle valve is opened therewith against the opposition of saidspring.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION 5 Referring to thedrawing, numeral Idenotes the body of an internal combustion engine, andnumeral 2 denotes a suction opening thereof, which is in communicationwith a carburetor 3 and an air cleaner (not shown) to receive externalair by means of a suction pipe 4. The suction pipe 4 has a section 5 inwhich a fuel-air mixture travels to the suction opening 2. A manuallyoperable throttle valve 6 in the carburetor 3 constitutes a firstthrottle valve and a second throttle valve 7 is provided downstream ofvalve 6. At the time of an engine brake operation when the firstthrottle valve 6 is closed, a large negative pressure is produced in thepassage 5 downstream of valve 6. A negative pressure operated ap paratusA is adapted to close the second throttle valve 7 by the a negativepressure existing in passage 5. The negative pressure operated apparatusA comprises a casing 8 whose interior is divided into upper and lowerchambers 10a and 10b by a the first throttle valve 6 is' closed atthe'time of an engine brake operation, the pressure in the interior ofthe chamber 10a drops to elevate the diaphragm 10, causing the secondthrottle valve 7 to undergo a closing operation through the connectingrod 12.

When the second throttle valve 7 is closed, any fuel adhering to thewalls of section 5 of pipe 4 upstream of valve 7 is prevented fromflowing into the engine 1 side but adhered fuel within the pipe 4downstream of valve 7 cannot be prevented from entering the engine andthis fuel acts to increase the fuel density in the air fuel mixture tounfavorably influence com bustion. To prevent this the followingarrangement is provided. Namely, the passage 5 downstream of the valve 7is provided with an air supply opening 14 which is in communication withthe outside air through a passage 13, so that by the produced negativepressure, external air is supplied to passage 5 through the opening 14for preventing an increase in the fuel-air ratio of the mixture.

If, however, the external air supply is continued, then thefuel-air'ratio will decrease which also causes unfavorable combustion inthe engine. The following arrangement is provided to prevent this.Namely,.the passage 13 is provided with a valve 15 for opening andclosing the same, and the valve 15 is urged to its closing side by aspring 16. The valve 15 is connected to a diaphragm 18 contained withina casing 17 so as to define lower and upper chambers 17a, 17b. The lowerchamber 17a is in communication with the negative pressure responsiveopening 11 and the chamber 17b is also in communication with opening 11through a small opening 24 in the diaphragm 18. Thus, if a negativepressure is generated, the diaphragm 18 is lowered to open the valve 15against the action of spring 16, so-that the interior of the passage 5is supplied with external air. As the upper and lower chambers [70 and17b within the casing 17 then become equalized in pressure through thesmall opening 24, the diaphragm l8 loses the bias force caused by thenegative pressure, so that the valve 15 is brought into a closedposition by the action of spring 16 to terminate the external air supplyautomatically.

If the second throttle valve 7 is designed to be of such an airtightsealing type that the front and rear thereof are fully sealed tightly inits fully closed position, then in the case when the engine brakeoperation with the valve 7 closed is continued, that portion of thepassage 5 downstream of valve 7 cannot be supplied with any fuel at allresulting in dryness of the walls of passage 5, so that when a burst offuel-air mixture is then supplied for acceleration power, the fuelcontained in the mixture is attracted to the dry walls which may producean accidental fire in the engine and the acceleration becomes rough. Toprevent this, the valve 7 itself is provided with a small hole 19providing communication between the front and rear thereof.Alternatively, the valve 7 is constructed to provide a gap'between theperiphery thereof and the wall of the passage 5 in its fully closedposition, so that fuel-air mixture may be passed even when the valve 7is fully closed.

It is desirable that, when the first throttle valve 6 is opened foracceleration, the second throttle valve 7 is also opened in accordancetherewith even if the negative pressure operated apparatus A remains inits operative condition. For satisfying this requirement, the followingarrangement is made. Namely, a link 20 connected at one end with thefirst throttle valve 6 is connected at its other end with the secondthrottle valve 7 through a long opening 21 and a pin 22, and a spring 23is interposed between an arm 7a connected to the second throttle valve 7and an arm connected to the rod 12 so that the valve 7 can be openedagainst the opposition of spring 23 even when the rod 12 is in itselevated position. If, accordingly, the first throttle valve 6 is openedfrom the condition illustrated in FIG. I, the second throttle valve 7 isalso opened against the opposition of spring 23 through the link 20,whereby the negative pressure downstream of the valve 7 is decreased andthis influences the diaphragm 10 through the negative pressureresponding opening 11 to cause downward movement of diaphragm 10 by thespring 9, thus conforming to the now open position of valve 7, Numerals7b and 12b denote engaging flanges projecting respectively from the arms70 and 12a.

The operation of the apparatus will next be explained in the following.

If the first throttle valve 6 is closed for engine braking, a negativepressure is produced downstream of valve 6 and the pressure influencesthe diaphragm 10 through the negative pressure responding opening 11 toclose the second throttle valve 7.

Accordingly, the valve 7 serves effectively to'prevent the liquid fuelpreviously adhered to the walls of the passage 5 from flowing into theengine 1 by the negative pressure.

The valve 15 is opened soon after the closing of the valve 7, so thatthe portion of the passage 5 downstream of valve 7 will be supplied withexternal air and thereby any increase of the fuel-air ratio by adheringfuel on the walls of passage 5 downstream of valve 7 is prevented. Thevalve 15 is then closed automatically with a slight delay, so thatcontinued supply of external air is prevented.

If the first throttle valve 6 is then opened for acceleration, thesecond throttle valve 7 is also opened in accordance therewith even ifthe negative pressure operated apparatus is kept in its operativecondition by the negative pressure which instantaneously remains andthus a rapid acceleration is obtained.

Thus, according to this invention, increase of the fuel-air ratio byadhered fuel upstream of the second throttle valve 7 is prevented by theclosing of said valve and further, increase of the fuel-air ratio byadhered fuel downstream of the second throttle valve 7 is prevented bythe external air supply to the passage downstream of valve 7, so thatthe influence of the adhered fuel can be substantially decreased. Thesupply of the external air is made only at the initial stage of theperiod after the closing of the second throttle valve, so that excessivedecrease of the fuel-air ratio due to the continual supply of theexternal air is prevented. Additionally, the second throttle valve isopened at the same time that the first throttle valve is opened foracceleration, so that the acceleration response is not adverselyaffected by the second throttle valve.

We claim:

1. In an engine having a main conduit for the supply of a fuel-airmixture thereto: a first throttle valve movable between open and closedpositions for controlling flow of the fuel-air mixture in the conduit, asecond throttle valve in said conduit downstream of the first throttlevalve, said first throttle valve producing substantial suction pressurein said conduit when closed, means responsive to the suction pressure insaid conduit and coupled to the second throttle valve to close thesecond throttle valve when the first throttle valve is closed, and meansresponsive to the suction pressure in the conduit to introduce ambientair into the conduit downstream of the second throttle valve when thefirst throttle valve is closed, said means for introducing ambient airinto said conduit comprising means for terminating the introduction ofthe air shortly after such introduction.

2. In an engine as claimed in claim 1 wherein said means for introducingambient air into said conduit comprises an air supply conduit, and valvemeans controlling introduction of ambient air into said air supplyconduit.

3. In an engine as claimed in claim 2 wherein said valve means comprisesa connection with said main conduit to enable the valve means to beoperated by the suction pressure prevailing in the main conduit whensaid first throttle valve is closed.

4. In an engineas claimed in claim 3 wherein said valve means comprisesa casing and a diaphragm in said casing dividing the same into first andsecond chambers, spring means acting on said diaphragm to urge the sameIn a direction to close said valve means, one of said chambers beingcoupled with said connection so as to be subjected to the pressure inthe main conduit, to open the valve means against the opposition of thespring means, by the suction pressure in the main conduit when the firstthrottle valve is closed, said means for terminating the introduction ofambient air into the main conduit being constituted by an opening insaid diaphragm to provide communication between the chambers and henceequalize the pressure therebetween a short time after said one chamberhas been subjected to said suction pressure in the main conduit. I

5. In an engine as claimed in claim 1 comprising means coupling saidfirst and second throttle valves to cause the second throttle valve tobe opened concurrently with the first throttle valve irrespective of thesuction pressure prevailing in the main conduit.

6. In an engine having a main conduit for the supply of a fuel-airmixture thereto: a first throttle valve movable between open and closedpositions for controlling flow' of the fuel-air mixture in the conduit,a second throttle valve in said'conduit downstream of the first throttlevalve, said first throttle valve producing substantial suction pressurein said conduit when closed, means responsive to the suction pressure insaid conduit and coupled to the second throttle valve to close thesecond throttle valve when the first throttle valve is closed, and meanscoupling said first and second throttle valves to cause the secondthrottle valve to be opened concurrently with the first throttle valveirrespective of the suction pressure prevailing in the main conduit,said means coupling the first and second throttle valves comprising alink connecting said throttle valves, and spring means between saidsecond throttle valve and said means which closes the second throttlevalve in response to the suction pressure in said main conduit whereby,when the first throttle valve is opened, the second throttle valve issimultaneously opened against the opposition of said spring means.

7. In an engine as claimed in claim 6 wherein said means which closesthe second throttle means comprises a casing, a displaceable diaphragmin said casing dividing the same into first and second chambers, meanscoupling the diaphragm with said second throttle valve to operate thelatter in accordance with displacement of the diaphragm, a spring actingon said diaphragm to urge the same in a direction tending to open thesecond throttle valve, and means connecting one of the chambers with themain conduit to provide communication therebetween such that suctionpressure in the main conduit will act in said one chamber and displacethe diaphragm against the action of the spring and cause the secondthrottle valve to close.

8. In an engine as claimed in claim 7 wherein said second throttle valvehas an opening therein providing communication in said main conduitupstream and downstream of the second throttle valve.

1. In an engine having a main conduit for the supply of a fuelair mixture thereto: a first throttle valve movable between open and closed positions for controlling flow of the fuel-air mixture in the conduit, a second throttle valve in said conduit downstream of the first throttle valve, said first throttle valve producing substantial suction pressure in said conduit when closed, means responsive to the suction pressure in said conduit and coupled to the second throttle valve to close the second throttle valve when the first throttle valve is closed, and means responsive to the suction pressure in the conduit to introduce ambient air into the conduit downstream of the second throttle valve when the first throttle valve is closed, said means for introducing ambient air into said conduit comprising means for terminating the introduction of the air shortly after such introduction.
 2. In an engine as claimed in claim 1 wherein said means for introducing ambient air into said conduit comprises an air supply conduit, and valve means controlling introduction of ambient air into said air supply conduit.
 3. In an engine as claimed in claim 2 wherein said valve means comprises a connection with said main conduit to enable the valve means to be operated by the suction pressure prevailing in the main conduit when said first throttle valve is closed.
 4. In an engine as claimed in claim 3 wherein said valve means comprises a casing and a diaphragm in said casing dividing the same into first and second chambers, spring means acting on said diaphragm to urge the same in a direction to close said valve means, one of said chambers being coupled with said connection so as to be subjected to the pressure in the main conduit, to open the valve means against the opposition of the spring means, by the suction pressure in the main conduit when the first throttle valve is closed, said means for terminating the introduction of ambient air into the main conduit being constituted by an opening in said diaphragm to provide communication between the chambers and hence equalize the pressure therebetween a short time after said one chamber has been subjected to said suction pressure in the main conduit.
 5. In an engine as claimed in claim 1 comprising means coupling said first and second throttle valves to cause the second throttle valve to be opened concurrently with the first throttle valve irrespective of the suction pressure prevailing in the main conduit.
 6. In an engine having a main conduit for the supply of a fuel-air mixture thereto: a first throttle valve movable between open and closed positions for controlling flow of the fuel-air mixture in the conduit, a second throttle valve in said conduit downstream of the first throttle valve, said first throttle valve producing substantial suction pressure in said conduit when closed, means responsive to the suction pressure in said conduit and coupled to the second throttle valve to close the second throttle valve when the first throttle valve is closed, and means coupling said first and second throttle valves to cause the second throttle valve to be opened concurrently with the first throttle valve irrespective of the suction prEssure prevailing in the main conduit, said means coupling the first and second throttle valves comprising a link connecting said throttle valves, and spring means between said second throttle valve and said means which closes the second throttle valve in response to the suction pressure in said main conduit whereby, when the first throttle valve is opened, the second throttle valve is simultaneously opened against the opposition of said spring means.
 7. In an engine as claimed in claim 6 wherein said means which closes the second throttle means comprises a casing, a displaceable diaphragm in said casing dividing the same into first and second chambers, means coupling the diaphragm with said second throttle valve to operate the latter in accordance with displacement of the diaphragm, a spring acting on said diaphragm to urge the same in a direction tending to open the second throttle valve, and means connecting one of the chambers with the main conduit to provide communication therebetween such that suction pressure in the main conduit will act in said one chamber and displace the diaphragm against the action of the spring and cause the second throttle valve to close.
 8. In an engine as claimed in claim 7 wherein said second throttle valve has an opening therein providing communication in said main conduit upstream and downstream of the second throttle valve. 